Increased Perceived Effort during Low-Intensity Exercise Linked to Type 2 Diabetes

Abstract

Exercise is a cornerstone of type 2 diabetes (T2D) treatment, but most people with T2D are sedentary. We identified a novel behavioral barrier to exercise in women with T2D compared to nondiabetic women — greater effort during low intensity exercise. We hypothesized that the presence of T2D would confer greater effort for adults across a range of exercise intensities, even when controlling for fitness. As T2D decreases fitness more in women than men, we also hypothesized sex would modify this association. We analyzed secondary data from past sedentary, overweight research participants with and without T2D who were free of cardiopulmonary comorbidities. During graded exercise tests to assess fitness (VO2peak), we repeatedly measured objective effort (heart rate (HR)) and subjective effort (Borg Rating of Perceived Exertion (RPE)). We plotted the rise of RPE and HR, respectively, against increases in relative work rate (%VO2peak: VO2 at work rate divided by VO2peak) at lower intensities below anaerobic threshold (AT) and higher intensities above AT. Adults with T2D (n=57) had similar age and adiposity as those without T2D (n=55), but had lower VO2peak: 20.7± 4.5 vs. 24.5 ± 6.6 ml/kg/min (p<0.05). Below AT, people with T2D had a steeper rise in RPE for each unit increase in %VO2peak than those without T2D (p=0.0029), and this finding was more pronounced in men than women (p=0.004). T2D status did not influence the association of %VO2peak and RPE above AT, or the association of HR and %VO2peak either below or above AT. People with T2D have significantly greater RPE during lower intensity exercise below AT as compared to people without T2D. This finding was not explained by fitness differences and, counter to our hypothesis, was more significant in men. We found no group differences in RPE at higher intensity exercise where physiological inputs tend to dominate behavioral predictors of effort. Future work should further characterize sex-specific mechanisms of exercise effort for people with T2D. Disclosure A.G. Huebschmann: Research Support; Self; Merck & Co., Inc.. M. Wahl: None. R.L. Scalzo: None. D. Rafferty: None. J.G. Regensteiner: None.